1. Field of the Invention
The present invention relates to semiconductor packages and, more particularly, to a connection structure for connecting circuit substrates.
2. Description of the Related Art
Integrated circuits (IC) have specific needs. Functionally, they require signal and power supplies. ICs can operate at high temperature and require heat dissipation. Furthermore, ICs damage easily by humidity, shock or thermal stress. Proper packaging satisfies these requirements.
In semiconductor package fabrication, circuit substrates or package substrates may use lead frames, printed circuit boards, ceramic substrates or tape wiring substrates. Strip-type circuit substrates may be used for simultaneous fabrication of a plurality of semiconductor packages. Single-type circuit substrates may be used for a single semiconductor package.
Tape wiring substrates and printed circuit boards may be flexible and thin, for example 150 μm to 200 μm thick, allowing the semiconductor packages to be fabricated with a reel-to-reel process. In a reel-to-reel process, the strip-type circuit substrates are wound on two reels and spaced at predetermined intervals and move from one reel to the other reel. The semiconductor package fabricating method using the reel-to-reel process allows mass production of packages, thereby increasing productivity. In conventional reel-to-reel processing, when a circuit substrate 10 (“a first circuit substrate”) reaches its end, a new circuit substrate 20 (“a second circuit substrate”) should be connected to the first circuit substrate 10). In general, the ends of the first and second circuit substrates 10, 20 are cut and connected to each other using an adhesive tape 30 to form a connected portion 40.
Currently, the connection between the circuit substrates 10 and 20 depends on the adhesive tape 30. The tensile strength of the connected portion 40 decreases considerably compared with an intact circuit substrate.
The reel-to-reel process occasionally deforms or otherwise damages the connected portion 40. Thus, a poorly connected portion may tear off at a tape feeder (not shown) or cause ajam.
Further, if the adhesive tape 30 expands, a gap between the first circuit substrate 10 and the second circuit substrate 20 occurs, causing a transfer fault. Specifically, the tape feeder utilizes guide holes formed on the circuit substrate at predetermined intervals and feeds the circuit substrate. If the adhesive tape 30 connecting the circuit substrates 10 and 20 expands abnormally, the guide holes in the connected portion 40 have irregular pitches, consequently generating the transfer fault. Evading detection with the naked eye, this expansion range of the adhesive tape 30 generally resides between 120 μm and 130 μm, as shown in FIG. 5.